This invention relates to an apparatus for holding concrete forms together or in place, while concrete is being placed, or for any number or reasons a rod must be held.
Concrete forms are typically held together by standard form ties while placing concrete. Forms are manufactured to have a standard spacing for which the ties are made. If this spacing deviates from the standard spacing, then metal pencil rods and rod clamps are typically used to hold the non-standard forms together. The rod clamps that are used are conventional and have been in use for many years.
Conventional rod clamps are typically in the form of a metal casting having a hole through which a form tie or pencil rod (hereinafter referred to as rods) can be passed. A bolt is threaded into the casting in a direction perpendicular to the rod, so that the bold can be tightened to clamp against the rod and secure it in place within the casting. The casting has a flat side adapted to rest against a concrete form, and is sufficiently large to prevent the casting from slipping through the form when pressure is applied by the poured concrete. Rod clamps are normally placed on both sides of concrete forms, and must be held tight against the form while concurrently tightening the bolt to hold the rod in place. The bold must be sufficiently tightened to secure the rod, yet not so tight as to sever the rod.
Rod clamps of the type described above are widely used and work well if the bolts are not fouled, such as with concrete or corrosion. However, fouling is inevitable under the conditions in which the clamps are used. Furthermore, the bolt threads can eventually become stripped due to over-tightening or repetitive use. However, damage to the rod and stripping of the bolt threads are often not discovered until the concrete pressure is applied, at which point the clamp is no longer able to secure the forms and the forms give under the pressure from the concrete. If a clamp fails, the forms must be braced in some manner to keep the concrete from bulging the forms.
An alternative to the rod clamp described above comprises a metal piece through which a rod is passed. The metal piece does not use a bolt to secure the rod, but instead uses a notched hinged piece that is adapted to bias against the rod. This type of rod clamp has not been as widely adopted because the notch is prone to wear.